1. Jeff says:

For questions 1 through 10 determine the number of significant figures in the following numbers.

1) The number is (400). Type the number of significant figures.

2) The number is (450). Type the number of significant figures.

3) The number is (455). Type the number of significant figures in the box below.

4) The number is ( 200. ). Type the number of significant figures.

5) The number is (100.00).Type the number of significant figures in the box below.

6) The number is (501). Type the number of significant figures in the box below.

7) The number is (0.006). Type the number of significant figures in the box below.

8) The number is (0.0617). Type the number of significant figures in the box below.

9) The number is (97.016). Type the number of significant figures in the box below.
10) The number is (10.01). Type the number of significant figures in the box below.

11) Define significant figure.

12) Explain what determines the number of significant figures a scientist should use.

13) Define accuracy.

14) Define precision.

15) A calculation based upon __________is only as accurate as the device that made the measurement.

16) We can always make a perfect measurement.

True
False

17) What is the function of the arm on the microscope?

18) The tube that supports the eyepiece.

19) Which piece of the microscope is a large lens with a high magnifying power?

20) The platform on which a slide is placed is called the _______________.

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SIGNIFICANT FIGURES, PRECISION, AND ACCURANCY

Scientific Investigation (03:41)

Even when collecting data as a part of an experiment, scientists must be aware of the proper method of reporting the data. The numbers used in scientific research are called significant figures. Significant figures are those numbers that are factually known for certain plus one estimated figure. The number of significant figures is determined by the tool(s) that the scientist uses. As an example, if a scale measures mass in pounds, the scientist can only give his or her answers in pounds. The scientist can not say that something has a mass of 2 or 3 lbs. All measurements must be given in exact pound increments. If a scale records in half pound increments, the scientist could report his or her findings to the nearest half pound. (1.5 lbs, 3.5 lbs, 4.0 lbs etc) In this case, there are two significant figures, the pound and the half pound.

Significant Figures
A calculation based upon measurement is only as accurate as the device that made the measurement.

The degree to which a measurement is accurate is expressed by the number of significant figures used in the numeric result. These are rules for dealing with numbers and calculations based upon measurement:

All digits (1 to 9) are significant.

Zeros between significant digits are always significant.

Trailing zeros are significant only if the number contains a decimal point.

Leading zeros used to place the decimal point are not significant.

Zeros following the decimal are always significant.

For multiplication and division: the answer has the same number of significant figures as the lowest measurement’s significant figures.

For addition and subtraction: the answer has the same number of decimal places as the measurement with the fewest decimal places.

If a distance measured is 1.45 meters, there are 3 significant figures.

If it takes a car 0.19 seconds to travel the given distance, there would be 2 significant figures

Think of this: Speed equals Distance divided by Time

If a person wants to find the speed of the car, they need to divide the distance by the time. However, the scientist can not give an answer using this many decimal places. The correct number of significant figures must be used.

As we look at the numbers used to calculate the speed, the distance has 3 significant figures while the time has only 2 significant figures. The correct amount of numbers to be used in determining the answer should match the fewest number of significant figures in the calculations used to solve the problem. In this case, the fewest amounts of significant figures is 2.

The answer, 7.6315789, must be rounded to only 2 numbers.

Since two numbers can be kept, one must look at the third number and determine how to round the second number.

If the third number is equal to or greater than 5, the second number is rounded up.

If the number is less than 5, the second number is rounded down.

The original extended answer was 7.6315789 and the third number in this case is three. This means the scientist needs to round